Leave this place at once. (Order)
Get lost. (Order)
Please help me. (Request)
Work hard. (Advice)
Let’s go for a walk. (Suggestion)

Exclamatory sentences
Sentences which express some strong feelings or emotions such as joy, sorrow, regret, surprise, wonder etc., are called exclamatory sentences.
What a marvelous sight!
How beautiful the flower is!
Hurrah! We have won.
Alas! She is no more.

Optative sentences
Sentences which express an ardent wish, prayer, curse etc., are called optative sentences.
May you live long!
May God help you!
Notes:
Assertive and imperative sentences are followed by a full stop. Interrogative sentences are followed by the sign of interrogation or question mark (?). Exclamatory and optative sentences are followed by the sign of exclamation (!). Note that in exclamatory sentences, sometimes, the interjection alone is followed by the exclamatory mark.